So-called cyclones or, in general, centrifugal separators are utilized for the separation of solid or liquid materials from flowing gases or liquids. The conventional arrangements have the drawbacks that the high rotational speeds necessary for efficient separation can be attained only with great expenditure of energy, and that the conventional cyclones have a relatively large-sized structure.
DE-A-2,647,486 discloses a hydrocyclone wherein special steps are taken to achieve preclassifying of the suspension to be purified in the hydrocyclone as early as within the inlet duct. For this purpose, the provision is made, in detail, that the entering stream of the suspension is divided into several component streams which are not to be combined any more even at a later point in time (see, in particular, pages 10 and 11 of DE-A-2,647,486).
Furthermore, there is no additional acceleration of the rotary movement in the hydrocyclone according to DE-A-2,647,486, and a product discharge pipe and a dirt discharge means are included. The fact that the dirt discharge means tapers in the shape of a truncated cone is of no significance for the separating effect since separation takes place primarily in an annular chamber, the walls of which are designed to be of cylindrical shape.
The centrifugal dust separator known from DE-C-883,555 comprises a displacement member tapering in the flow direction, whereas the wall has a cylindrical shape so that here, again, there cannot be an acceleration of the rotary movement. Furthermore, clean air is withdrawn only unilaterally via a clean air pipe.
The remarks set forth in connection with DE-C-883,555 also apply with respect to DE-C-688,803 since also in this reference a displacement member tapering in the flow direction is arranged within cylindrical outer walls. Also in DE-C-688,803, the purified medium is withdrawn merely on one side. An acceleration of the rotary motion cannot be expected in the device according to DE-C-688,803 on account of the ribs which extend in the longitudinal direction.
An apparatus disclosed in French A-2,274,363 comprises a baffle member known in a similar form from the two German patents discussed farther above.
In British C-374,382, the actual separating chamber is of cylindrical design so that acceleration of the rotary movement with reduction in the radius of the rotary movement does not occur. In British C-374,382, the purified medium is not withdrawn in opposite directions from the separating chamber.
U.S. Pat. No. 4,420,314 shows a separator with a cylindrical separating chamber shown especially in FIG. 4, wherein the medium to be separated is to collect. The arrangement of guide vanes is known from U.S. Pat. No. 4,420,314. However, in the separator known from U.S. Pat. No. 4,420,314, there is no acceleration of the rotary movement, and withdrawal of the purified medium is not effected through mutually opposed outlet openings.
Centrifugal separators with dip pipes are known per se from DE-A-2,832,097; DE-A-2,945,951; and DE-A-3,615,747. None of these conventional arrangements provides that the crude gas (namely the mixture of material and medium) is conducted from the inlet into the separating chamber.
In these arrangement, rather, crude gas exits again directly downstream of the inlet, and only a small partial quantity of crude gas can evolve into an eddy in these systems; more than half of the mixture fails to enter the separating chamber directly.
A dust remover has been known from "Handbuch der Entstaubung" [Manual of Dust Removal], published in 1964 by the printing department of Maschinenfabrik BETH GmbH (see pages 94 and 95); this dust remover is also called "Van-Tongeren dust separator" (see loc. cit. FIG. 47). In the Van-Tongeren dust separator, the gases to be freed of dust are set into a rotational movement with an only weak radial component in a fluidizing chamber. The dust particles migrate to the wall of the fluidizing chamber where they are suctioned off together with a small partial gas stream and finally are precipitated in a cyclone having a correspondingly smaller diameter. The thus-cleaned gases exit from the fluidizing chamber after reversal of their direction of rotation through a cylindrically aligned baffle system; by the deflection movement, any relatively large particles that have been entrained are to be flung away toward the outside. This arrangement of a dust remover, although offering the advantage of a compact arrangement possibility since the fluidizing chamber can be accommodated, in case of removing dust from flue gases, in a flue that is needed anyway, does include the disadvantages that this structure can hardly meet any more sophisticated requirements than an individual cyclone having a correspondingly larger diameter.